The present invention relates to exposure masks for use with micro cameras, and more particularly to exposure masks which can automatically set micro cameras to proper microfilming formats when mounted in the micro cameras.
For conserving storage space, it is a widespread practice to microfilm documents by means of micro cameras. The micro camera has a camera assembly or camera head including an exposure mechanism placed above a stationary table on which documents are placed in position to be microfilmed. In accordance with the types of documents, indexing mode of information contained in microfilm, etc., there are various standardized microfilming formats which are selectively adopted for the purposes of microfilming. The selection of suitable formats is made based on the size of the document-images on film, the necessity of recording data together with the document-images on film, the location of the data on the film, etc.
Micro cameras usually have a predetermined, unchangeable camera format for microfilming documents. This type of micro camera is, therefore, disadvantageous in applications wherein it is necessary to microfilm different types of documents in various formats by use of a single micro camera. If the size of the frames of the document images is made changeable by using various types of exposure masks, it is necessarily required to adjust the micro cameras so as to change the forwarding length of the film in accordance with the frame sizes in order to keep the distance between frames constant for all microfilms with different frame sizes and to change the location where the data associated with each document-image is to be recorded on film.
The micro camera described above has the disadvantage that it is difficult to embody the micro camera in a practical environment. In particular, micro cameras used heretofore are difficult to adjust manually.